1. Field of the Invention
The present invention relates generally to solid state imagers and particularly to a solid state image pick-up apparatus of a CCD (charge-coupled device) type.
2. Description of the Prior Art
So far it has been proposed to control sensitivity by controlling an accumulation time in a conventional solid state image pick-up apparatus of a CCD (charge-coupled device) type. As, for example, shown in FIG. 1B, the accumulation end time is made constant and the accumulation start time is controlled to make sensitivity control. FIG. 1A illustrates a vertical synchronizing pulse VD.
In the prior art, an accumulation time from about 1/500 to 1/2000 second is selected for a fast moving object to be picked up and analyzed in its operation and so on.
According to the solid state image pick-up apparatus of which the sensitivity is controlled by controlling the charge accumulation time as described above, if the charge accumulation time is reduced, the moving picture is felt to be discontinuous.
Further, according to the solid state image pick-up apparatus in which a short charge accumulation time is selected for a fast moving object to be picked up, the accumulation time occurs once during one vertical period and thus may fail to catch the desired object, resulting in no object image being obtained. As a method of picking up a high-speed moving object without such problem, the time of illumination from light source is controlled, but this method needs a special light source.